Material characterization at high strain by adapted tensile tests

The strength of materials at high strain levels has
been determined using the so-called Continuous-Bendingunder-
Tension (CBT) test. This is a modified tensile test
where the specimen is subjected to repetitive bending at the
same time. This test enables to create high levels of uniform
strain. A wide variety of materials has been tested this way.
The strength of the material after CBT testing has been
measured in different ways: by secondary tensile tests, by
interrupted CBT tests, and directly from the fracture in the
CBT test. All methods yield similar results: the strength is
largely unaffected by the cyclic pre-deformation and mainly
depends on the overall increase in length. Only for multiphase
materials the strength shows a minor influence of
CBT test conditions. The hardening follows the extrapolated
hardening observed in a conventional tensile test, except for
brass. This test method can potentially be used for measuring
hardening curves at high strain levels.